This invention refers to an analog-to-digital (A/D) flash converter used to convert or to measure an analog signal Vin (input voltage) in a digital number.
The existing full flash converters use a schematic with comparators having the same voltage increment between two consecutive comparators. (e.g. An 8 bit full flash converter uses 255 comparators for 2.55 V, with 10 mV voltage increment). The converter will change the digital output with one for each 10 mV change of the analog input signal. The voltage increment is provided by a 256 resistor ladder.
The existing two-step or semi-flash A/D converter has 31 comparators and consists of two 4-bits flash conversions, one for least significant bits (LS) and one for most significant bits (MS). The 4 LS bits are combined with the 4 MS bits as the 8-bit digital number.
The disadvantages of the full flash converter are the high number of comparators and a complicated encoder, which will increase the converter volume and price. The semi-flash converter still has a part of the above disadvantages.